Oil well treating method and composition

ABSTRACT

A particular simple method and class of organic polycationic polymer compositions are provided for treating earthen formations such as in oil wells to stabilize clay against dispersion and expansion due to water.

This application is a continuation of application Ser. No. 901,664,filed May 4, 1978, which is a continuation-in-part of application Ser.No. 714,213, filed Aug. 13, 1976, now abandoned.

Production of petroleum hydrocarbons is often troubled by the presenceof clays and other fines capable of migrating in the formation.Normally, these fines, including the clays, are quiescent causing noobstruction to flow to the well bore via the capillary system of theformation. When the fines are disturbed, they begin to migrate in theproduction stream and, too frequently, they encounter a constriction inthe capillary where they bridge off and severely diminish the flow rate.

The agent that disturbs the quiescent fines is frequently theintroduction of a water foreign to the formation. The foreign water isoften fresh or relatively fresh water compared to the native formationbrine. The change in the water can cause fines to disperse from theirrepository or come loose from adhesion to capillary walls.

Sometimes the loss of permeability is due to clay swelling withrelatively fresh water without migration. But, often clay swelling isaccompanied by migration of fines. Sometimes non-swelling clays canrespond to the foreign water and begin to migrate. It is believed thatswelling clays are the major mechanism of fines migration and/orswelling, because when formation cores are analyzed, the presence ofswelling clays are an excellent indicator that the formation will besensitive to foreign water intrusion, while the presence of non-swellingclays only is inconclusive.

Generally, swelling clays are in the smectic group including clayminerals such as montmorillonite, beidellite, nontronite, saponite,hectorite and sauconite. Of these, monmorillonite is the clay mineralfound most commonly in formation core analysis. Montmorillonite iscommonly associated with clay minerals known as mixed-layer clays. Forfurther information, refer to Jackson's TEXTBOOK OF LITHOLOGY, pages 95to 103.

Migrating fines including a host of clay and other minerals in minuteparticle size, for example: feldspars, fine silica, allophane, biotite,talc, illite, chlorite and the swelling clays themselves. For additionalinformation, see Theng's THE CHEMISTRY OF CLAY-ORGANIC REACTIONS, pages1 through 16.

Clays can also cause trouble in areas other than permeability reduction.When they are a component in shales, sandstones, or other formations,contact with a foreign water or at times with any water can cause theformation to lose strength or even disintegrate. This is a problem inbuilding foundations, road beds, drilling wells and any situation wherethe formation strength is important.

There have been numerous attempts to control the ill effects of water onclay and/or other fines. These have been principally in the oilindustry. One idea is to convert the clay from the swelling sodium form(or the more rare swelling lithium form) to another cation form whichdoes not swell as much.

Example cations that form relatively non-swelling clays are potassium,calcium, ammonium and hydrogen ions. When a solution of these cations,mixed or individually, flows past a clay mineral, they readily replacethe sodium ion and the clay is transformed to a relatively non-swellingform (refer to Theng, Tables 2, 3, and 4). The use of acid, potassium,calcium, or ammonium ions to exchange for sodium ion has been successfulin preventing damage to formations susceptible to plugging ordisintegrating due to clays in their compositions.

The prior art and conventional features useful with this invention aredescribed in references cited and/or discussed herein. Each referencecited or discussed herein is incorporated herein by reference to anyextent deemed necessary for any purpose. Prior art references are citedas follows:

    ______________________________________                                               2,761,843                                                                            3,625,684                                                              2,801,984                                                                            3,660,431                                                              2,801,985                                                                            3,666,810                                                              2,940,729                                                                            3,738,437                                                              3,334,689                                                                            3,741,307                                                              3,382,924                                                                            3,827,495                                                              3,419,072                                                                            3,827,500                                                              3,422,890                                                                            3,833,718                                                              3,483,923                                                                            3,974,220                                                              3,494,965                                                                            4,069,365                                                              3,578,781                                                                            4,073,763                                                              3,603,399                                                              ______________________________________                                    

24. Barkman, J. H.; Abrams, A.; Darley, H. C. H.; & Hill, H. J.; "An OilCoating Process to Stabilize Clays in Fresh Water Flooding Operations,"SPE-4786, SPE of AIME Symposium on Formation Damage Control, NewOrleans, La., Feb. 7-8, 1974.

25. Coppel, Claude E.; Jennings, Harley X.; & Reed, M. G.; "FieldResults From Wells Treated With Hydroxy-Aluminum," JOURNAL OF PETROLEUMTECHNOLOGY (September 1973) pp. 1108-1112.

26. Graham, John W.; Monoghan, P. H.; & Osoba, J. S.; "Influence ofPropping Sand Wettability of Productivity of Hydraulically Fractured OilWells," PETROLEUM TRANSACTIONS, AIME, Vol. 216 (1959).

27. Hower, Wayne F.; "Influence of Clays on the Production ofHydrocarbons," SPE-4785, SPE of AIME Symposium on Formation DamageControl, New Orleans, La., Feb. 7-8, 1974.

28. Hower, Wayne F.; "Adsorption of Surfactants on Montmorillonite,"CLAYS AND CLAY MINERALS, Pergamon Press (1970) Vol. 18, pp. 97-105.

29. Hoover, M. F., and Butler, G. B.; "Recent Advances in Ion-ContainingPolymers," J. POLYMER SCI, Symposium No. 45, 1-37 (1974).

30. Jackson, Kern C.; TEXTBOOK OF LITHOLOGY, McGraw-Hill Book Company(1970) (Library of Congress Catalogue Card No. 72-958LO) pp. 95-103.

31. Theng, B. K. G.; THE CHEMISTRY OF CLAY-ORGANIC REACTIONS, John Wiley& Son (1974) (Library of Congress Catalog Card No. 74-12524) pp. 1-16.

32. Veley, C. D.; "How Hydrolyzable Metal Ions Stabilize Clays ToPrevent Permeability Reduction," SPE-2188, 43rd Annual Fall Meeting ofSPE of AIME, Houston, Tex. (Sept. 29-Oct. 2, 1968).

33. Milchem Incorporated, "Milchem's SHALE-TROL Sticky Shale Can't StopYou Anymore," DF-5-75 1M.

34. Chemergy Corporation, "Maintain Maximum Production With PermaFIX andPermaFLO Treatments for CLAY/FINE and SAND CONTROL."

However, the exchanging of other ions for sodium on clay is only atemporary remedy. When a well is produced, the presence of sodium ion inthe formation water will enable sodium ion to counter replace hydrogen,potassium, ammonium or calcium ion quickly. As a result, the clay isreturned to the swelling or dispersible form, ready to cause damageshould a foreign water be introduced. Veley et al. U.S. Pat. No.3,382,924 column 3, lines 45 through 75 and including lines 1, 2 and 3,column 4, employes calcium ion to replace the sodium ion in the coreclays (lines 51-53). The calcium ion protects the core (lines 54-57). Iftreatment is omitted (lines 58-63), then the sodium chloride brine (line64) will counter replace the calcium and the core will be severelyrestricted in flow in step 7 (lines 65-68) as stated in line 75, column3, and lines 1-3, column 4.

Since simple cations are easily exchanged away and the treatment is notpermanent, there have been endeavors to improve on treatment withhydrogen, potassium, calcium or ammonium ions (and probably someothers). Among the more successful are the inorganic polycationicpolymers or complexes. The most prominent among these are ZrOCl₂ andAL(OH)xCly. Veley et al. U.S. Pat. No. 3,382,924 and the article "HowHydrolyzable Metal Ions Stabilize Clays to Prevent PermeabilityReduction" cover the subject of ZrOCl₂ with the polycationic nature ofZrOCl₂ explained in SPE-2188. Hydroxy-aluminum reaction products of HCland Al(OH)₃, with formulae ranging from Al(OH)₁.5 Cl₁.5 to Al(OH)₂.7Cl₀.3, is disclosed in the Marion G. Reed patents and the article "FieldResults From Wells Treated with Hydroxy-Aluminum."

The inorganic polycationic polymers or complexes are quite successful incontrolling migrating fines and swelling clays. However, they havelimitations of several sorts. Hydroxy-aluminum requires a cure timeafter it is placed in the presence of clay; this cure time is adisadvantage in that rig and production time is consumed during thewait. Hydroxy-aluminum can tolerate only a limited amount of carbonatematerial in the formation. Also, hydroxy-aluminum can be removed by asubsequent acid treatment of the formation. Zirconyl chloride is limitedin the pH range of the placement fluid and can be removed by acid undercertain conditions. For other type clay treatments see U.S. Pat. No.3,741,307.

Another treatment to control the undesired effects of swelling clays andmigrating fines is the use of organic cationic surfactants. If theorganic part of the cation is large enough, the organic cation is notreadily replaced. See the references by Wayne F. Hower. Cationicsurfactants have a tendency to oil wet the formation which some personsconsider an advantage (see reference by J. H. Barkman). However, manypetroleum engineers consider oil wetting of the formation to be adisadvantage because it retards the production of oil and acceleratesthe production of aqueous fluids (see reference by J. W. Graham).

This invention is the use of organic polycationic polymers to prevent orreduce the ill effects of swelling clays and/or migrating fines in earthformations. An aqueous solution of the organic polycationic polymer isflowed past the clay to be treated without dispersing the formationparticles until the organic polycationic polymer replaces the claycation, normally sodium ion, and transforms the clay to a more stableform that is much less likely to swell or migrate. The organicpolycationic polymers of this invention have several advantages. Theycan be applied to all types of formations regardless of carbonatecontent. They are acid resistant, i.e., the formation can be treatedwith acid later, without destroying their clay treating ability. Theyare placeable in water solutions including a wide range of brines andacids. The treatment with organic polycationic polymers is essentiallypermanent. The organic polycationic polymers are very resistant to beingremoved by brines, oils, or acids. Oil wetting of the formation can beavoided. They can be made pH tolerant. No cure time is required; testsindicate that less than one minute is required for adsorption on theclay to be complete. Very low permeability formations can be treated.They can give high permeability retention after the clays and fines aretreated. Wide formation temperature ranges can be accommodated. Thepolymers were tested at 70°-300° F. but the range could be wider. Somepolymers have been tested up to about 500° F. with flowing steam andshowed no sign of allowing permeability reduction in clay-sand packs.

There is a wide range of applications for the organic polycationicpolymers. These applications involve using the organic polycationicpolymers alone, as the primary treating agent, or as an auxilliary inother treatments.

The invention of this application comprises basically a certain class oforganic polycationic polymers and methods of their application. Thepolymers have a molecular weight over about 800 or 1,000 and preferablyabove 1,500 and up to about 3,000,000 and preferably less than about100,000. The organic polycationic polymers can be applied to any earthenformation or permeable mass containing clay where clay swelling couldpresent a problem. The polymers can be used to treat both naturally andartifically consolidated structures or man-made consolidations.

Any suitable method of application can be used in view of thisdisclosure. For some applications such as surface or exposed structures,it may be desirable to merely spray the polymer onto the permeable mass.The essential feature is contact between the clay particles to betreated and the polymer. A preferred method uses a carrier fluid. Apreferred carrier fluid is water or an aqueous media. The water cancontain other ingredients which do not substantially interfere withdispersion or dissolution of the polymer in the media. The water carriermay be gelled or thickened for certain applications. Such ingredients oradditives can include salts, mineral acids, low molecular weight organicacids, cationic or nonionic surfactants (anionic surfactants can be usedwith a mutual solvent), wetting agents, or coupling agents such assilanes or conventional additives used in consolidation treatments,stimulation treatments or drilling of oil wells. The carrier fluid canalso be a normally liquid polar-substituted hydrocarbon such as analcohol. Normally, a polar hydrocarbon will be necessary tosatisfactorily disperse or dissolve the polymer within the carrier.Under certain conditions, the polymer may be dispersed or emulsified ina non-polar carrier liquid. The carrier fluid preferably has a boilingpoint in the range of about 25°-200° C. and a viscosity of less thanabout 10 cp. Higher viscosity fluids might be used for certainapplications (such as fracturing, sand consolidation, sand packing orgravel packing) but are generally not practical from pressure or pumpingrequirements. The organic polycationic polymer should be present in thecarrier fluid in a concentration within the range of about 0.01-25% byvolume of the carrier fluid. Lower or higher concentrations can be usedbut are generally not practical.

A preferred aqueous carrier fluid is a saline solution containing about0-40% salt up to about saturation limits at the applicable temperature.The preferred salt concentration is about 2-12% by weight; however,concentrations up to about 35% can be used, as well as fresh water. Thesalt can be an alkali metal salt, alkaline earth metal salt, ammoniumsalt or combinations thereof. These include the halides, sulfates,carbonates, oxides or combinations thereof. The halides of potassium,sodium, magnesium, calcium, ammonium and combinations thereof arepreferred due to economics and solubility. Aqueous acids of about thesame concentrations can also be used. These acids include acetic,formic, hydrofluoric, hydrochloric, nitric, phosphoric, sulfurous, andsulfuric. Low molecular weight organic acids such as acetic and sulfoniccan also be used under some conditions. Conventional additives such asinhibitors, surfactants, coupling agents, wetting agents and others canbe used where desirable and especially where the organic polycationicpolymer is used with conventional treatment procedures. The carrierfluid preferably contains salts or acids which will shrink or preventswelling until the polycationic polymer has treated the clay particles.Normally, the treatment is practically instantaneous with contactbetween the formation and treatment fluid. Use, production or flowthrough the formation can usually be resumed within several hours, e.g.2-3, and in practically all cases in less than 18 or 24 hours. Thecarrier fluid and formation are brought into contact by injecting thecarrier fluid into the formation, applying the fluid to the formation,or flowing the fluid past the formation in a manner to cause minimumdisturbance of individual particles within the formation. Thus, thetreatment procedure of this invention is useful where permeability islow and maintaining of maximum permeability is a critical feature.

In chemical grouting operations such as sealing leaks in dams, mines,tunnels, basements, and the like (see references Rakowitz U.S. Pat. No.2,940,729, Morgan U.S. Pat. No. 2,801,984, Roth U.S. Pat. No. 2,801,985and McLaughlin U.S. Pat. No. 3,334,689), there are occasions where thepermeability decreases and the formation refuses to take chemical grout.This is normally caused by pH or osmotic disturbance brought about byintroducing a foreign water (chemical grout) into the formation. Bypretreating the grout hole with an organic polycationic polymer, thepermeability can be maintained open so that sufficient chemical groutcan be injected until it spreads to a large enough radius to seal offleaks.

In the production of gas, oil and/or water wells a problem frequentlyarises where the soft formation breaks off around the well bore and sandis produced. Since production of sand is highly undesirable, severalmeans of stopping sand production have been devised, one of which isgravel packing. Gels and/or brines are used to wash gravel, usuallygraded sand or particulate material, into place around the well bore inthe producing interval.

In one technique the gravel or sand is allowed to settle and compact.Subsequently, a liner or screen is washed into the well and positionedacross the formation. The pack sand now restrains the formation sand andthe screen retains the pack sand. This permits the production of sandfree fluids. However, when the gravel is being pumped into place, theloose formation solids are pressed back, forming a compaction frontbetween the formation and pack sand. This front, particularly if itcontains clays, often restricts fluid flow into the well bore after thegravel pack is in place. The use of organic polycationic polymers in apreflush, in the gravel pack carrying fluid, or in a fluid after thegravel pack is in place, can eliminate or relieve the loss ofpermeability in the compaction front. Also, organic polycationicpolymers flushed out beyond the gravel pack vicinity can preventmigration of fines into the gravel pack where the fines often plug thegravel pack.

Fracturing with sand or sand packing any cavity may be similar to gravelpacking except that the grain size may be different. The use of organicpolycationic polymers in conjunction with sand fracturing produces thesame beneficial result.

Sand consolidation employes hard setting resins to stick sand grainstogether. The formation sand itself can be so treated or a pre-resincoated sand employed as a sand pack can be used. The use of organicpolycationic polymers in conjunction with sand consolidation can preventthe migration of fines and clays back into the sand consolidation massand reduce the plugging action of a compaction front, should one form.

In secondary recovery operations where waterfloods are used to recoveroil, frequently the only available water for injection into injectionwells is likely to cause clay swelling and/or fines migration which canplug the injection wells. Preliminary treatment of injection wells withorganic polycationic polymers before flooding with the suspect water canprevent damage by migrating fines and clay swelling. This isparticularly vital in the immediate vicinity of the well bore where thepermeability is so important. The treatment can be used to alter thewater wetting characteristics of a formation or prevent any decrease inoil permeability in any formation due to oil wetting of the formationwhere clay might present a problem.

Certain formations are naturally cemented or consolidated together withsubstances that are removed or weakened by water contact. As long ashydrocarbons are produced alone, the wells give little trouble. However,when the water table rises in the course of production and water startsto coproduce with the hydrocarbons, sand will start to produce.Sometimes the situation is so bad that hole collapse results. When theformation cementation material is clay, the treatment of the well borevicinity prior to water breakthrough can prevent sand production and/orhole collapse.

When oil and gas wells are cased, it is necessary to perforate thecasing or to drill out a section of open hole below the casing in orderto complete the well and start production. A hazard in this wellcompletion operation is that the fluid in the well bore will damage thepermeability because it often rushes into the formation when it isopened up. The well can be completed as an open hole, or by perforatingusing shaped charges or bullets. As a component in the completion fluid,organic polycationic polymers have a purpose of preventing damage topermeability should pressure in the well be higher than formationpressure and the well fluids enter the formation.

Acidizing is a common technique in the art of improving well production.Acid is pumped into the formation for the purpose of enlarging the poresand thus increasing permeability. Hydrochloric acid is commonly used incarbonate formations such as limestone and dolomite and hydrofluoricacid solutions are often used in sandstones. However, in someformations, acidizing loosens fines so that they migrate and causeplugging. A characteristic of these formations is that acidizingimproves production, but a decline in production rate soon sets in asfines migrate to plugging positions. The use of organic polycationicpolymers before, during, and/or after acidizing minimizes finesproduction.

Hydraulic fracturing in another common technique in the art of improvingwell production. The well bore is pressured up until the formationbursts and the resulting fracture exposes large areas of producingformation face. The cracks are normally prevented from healing closed bypumping sand into the fracture. However, fracturing fluid that bleedsinto the fracture face often interacts with clays and damagespermeability. This damage is particularly critical when the permeabilityis low, i.e., about 10 millidarcies to 0.1 millidarcy. The use oforganic polycationic polymers in conjunction with fracturing operationshas been quite successful.

It is much better to prevent damage by swelling clays and/or migratingfines than to try to correct the damage after it occurs. Much of thedamage is irreversible. However, in cases where the damage has alreadyhappened, the use of organic polycationic polymers as the primarytreating agent in conjunction with other treatments can restore much ofthe lost permeability.

Wells in the process of being drilled, particularly air or gas drilledwells, often are troubled by the swelling and heaving of formationstraversed by the well bore. These formations contain clay minerals, thatwhen wet with aqueous fluids, such as mist or foam drilling, will causesloughing of the formation, frequently causing a danger of sticking thedrill string and/or bit in the hole. Some of these formations arereferred to in the art as "gumbo shale." Treatment and/or impregnationof these formations with compositions of this invention can alleviatethe danger of swelling or heaving formations. The treatment can also beused in drilling or completion operations where two-phase fluids, suchas emulsion, foam, fog, smoke or gaseous dispersion, mist or slurry, areused.

The organic polycationic polymers of this invention can generally beconsidered quaternary polymers with nitrogen or phosphorous as thequaternary or cationic atom with an aliphatic, cycloaliphatic oraromatic chain. Trivalent or tertiary sulfur can substituted for thequaternary nitrogen or phosphorous in the polymers. The cationic atom tocarbon atom ratio is preferably about 1:2 to 1:36 and the molecularweight is above about 1,000. The organic polycationic polymer is polarand therefore generally soluble or readily dispersible in polar solventsor carrier fluids such as an aqueous media or an alcohol, or anothersubstitute hydrocarbon can be used as the carrier fluid where it isdesirable to avoid contact between water and the permeable mass orformation to be treated. Examples of these polycationic polymers includepolyethyleneamines, polyvinylpyridinium salts, or polyallylammoniumsalts.

Preferred organic polycationic polymers of this invention can becharacterized and illustrated by the following formula and examples.##STR1## wherein R₁ is an organic aliphatic, cycloaliphatic, or aromaticradical containing 2-40 carbon atoms or a hydrogen radical and when R₁is cycloaliphatic Z and R₂ can be in the ring;

R₂, R₃ and R₄ are organic radicals independently defined as R₁containing 0-6 carbon atoms and 0-2 oxygen or nitrogen atoms; when R₁ iscycloaliphatic it may or may not be in the organic polycationic polymerchain; when

Z is sulfur R₄ is not present;

Z is a cation such as those derived from nitrogen, phosphorous orsulfur;

X is an anion such as halide, nitrate, sulfate, bisulfate, carbonate,hydroxide, borates, oxides, azides, cyamides, phosphates, etc.;

n is an integer equal to the number of monomer units in the polymerrequired to give a molecular weight in the range of about 800-3,000,000and preferably at least about 1,000; and

m is an integer equal to the number of anions required to maintainelectronic neutrality.

The organic or hydrocarbon radicals can be linear, branched orcycloaliphatic radicals, aromatic radicals, unsaturated radicals,unsubstituted radicals or combinations thereof. The organic radicals canbe homoaliphatic or heteroaliphatic, i.e., may or may not contain otheratoms such as oxygen or nitrogen. The organic radicals can be homocyclicor heterocyclic, i.e., may or may not contain other atoms such as oxygenor nitrogen. Thus, the organic radicals can be substituted orunsubstituted alkyl, aryl or combinations thereof with each radicalhaving 0-40 and preferably 0-6 carbon atoms.

The above class of organic polycationic polymers can be divided into thefollowing preferred subclasses:

A. Alkyl Polycationic Polymers ##STR2## wherein R₁ is a divalent normalor branched chain alkylene group containing 2-40 carbon atoms,preferable range 2-12 carbon atoms;

R₂ is contained within R₁ ;

R₃ is normal or branched alkyl or hydrogen containing 0-6 carbon atomsand preferably 1-3 carbon atoms;

R₄ is a radical defined the same as R₃, but it may or may not beidentical to R₃, e.g., R₃ =methyl and R₄ =propyl; when Z is sulfur R₄ isnot present;

Z is a cation such as those derived from nitrogen, phosphorous, orsulfur;

X is an anion such as halide, nitrate, sulfate, hydroxide, etc.;

n is an integer equal to the number of monomer units in the polymerrequired to give a molecular weight in the range of about1,500-3,000,000; and

m is an integer equal to the number of anions required to maintainelectronic neutrality.

For the above subclass, preferred molecular weight ranges are up toabout 150,000, especially about 30,000-150,000 for minimum viscosity andabout 30,000-3,000,000 for higher viscosity aqueous solutions of thepolymers. One preferred group of this subclass is applied in a carrierfluid at a pH greater than about 4, especially in the range of about5-9. In another preferred group when Z is nitrogen, at least one of R₃and R₄ is not hydrogen, methyl, ethyl or propyl.

B. Heteroaliphatic Polycationic Polymers ##STR3## wherein R₁ is arylene,alkylene, arylalkylene, alkylarylene, alkenylene or combinationsthereof. When R₁ is alkyl it contains or has appended one or more heteroatoms or groups. When R₁ is aryl, or alkyl aryl it can contain or haveappended one or more hetero atoms or groups. R₁ can benormal-hetero-alkyl or it can be branched extensively through thehetero-atoms or groups. The hetero-atoms or groups may be ethylenic(--CH═CH--, acetylenic (--C.tbd.C--), aryl, or nitrogen, phosphorous, orsulfur, in regular covalent bonding, partially oxidized, e.g., sulfone,or in the onium state, other hetero atoms or groups may be oxygen,hydroxyl, carbonyl, or covalent halogen. With the exception ofethylenic, or aryl, a hetero atom or group is not bonded directly to Z.

R₂ is an unsubstituted alkylene or it can be defined as R₁ but it is notrequired to be identical to R₁. R₂ can be included in R₁.

R₃ can be alkyl containing 1-6 carbon atoms, hydrogen or it can bedefined as a monovalent form of R₁ but it is not required to beidentical to R₁.

R₄ can be defined as R₃ but it is not required to be identical to R₃.When Z is sulfur R₄ is not present.

Z is a cation such as those derived from nitrogen, phosphorous orsulfur.

X is an anion such as halide, nitrate, sulfate, hydroxide, etc.

n is an integer equal to the number of monomer units in the polymerrequired to give a polymer with a molecular weight in the range of about800-3,000,000.

m is an integer equal to the number of anions required to maintainelectronic neutrality.

The polymer can branch through R₁, R₂, R₃, or R₄ in such manner that themain polymer chain is an arbitrary choice and R₁, R₂, R₃, and R₄ arearbitrary choices around any particular Z. A preferred molecular weightrange is about 1,500-150,000.

A typical branched polymer is shown as follows: ##STR4## The anions areomitted for clarity.

C. Polycationic Polymers Containing Rings ##STR5## R₁ is alkylene,unsaturated alkylene, substituted alkylene, or substituted unsaturatedalkylene forming a heterocyclic ring including Z. The heterocyclic ringcan be aliphatic, olefinic or aromatic depending on the degree ofunsaturation. Substitutions can be alkyl, alkenyl, alkynyl, or arylbranches or substitutions can be hetero atoms or hetero groups containedin the ring, appended to the ring, or appended to the branches. Heteroatoms or groups can be phosphorous or sulfur (in regular covalent, oniumor oxidized state, e.g. phosphate or sulfone), nitrogen, oxygen,hydroxyl, carbonyl, or covalent halogen, a restriction being that thehetero atom or group is not bonded directly to Z.

R₂ is not included in R₁.

R₃ is a hydrogen radical or an organic radical containing 1-6 carbonatoms and 0-2 oxygen or nitrogen atoms. In the case of certain arylpolycationic polymers, with monomer units bonded through Z and elsewhereon the aryl, R₃ may be absent.

R₄ is defined the same as R₃ but is not required to be identical withR₃. When Z is sulfur R₄ is absent.

Z is a cation such as those derived from nitrogen, phosphorous orsulfur.

X is an anion such as halide, nitrate, sulfate, hydroxide, etc.

n is an integer equal to the number of monomer units in the polymerrequired to give a polymer with a molecular weight in the range of about800-3,000,000.

m is an integer equal to the number of anions required to maintainelectronic neutrality.

Bonds containing monomer units may be through Z, other hetero atoms, R₁(1 or 2 sites), or branches on R₁. A preferred molecular weight range isabout 1,500-150,000.

D. Pendent Polycationic Polymers ##STR6## wherein R₁ can be alkylene,alkenylene, alkynylene, arylene, and linkages or branches of these incombinations. R₁ can contain hetero atoms or groups in the pendentlinkage, on branch chains, on or in the polymer linkage. Hetero atoms orgroups can be phosphorous or sulfur (in regular covalent, onium, orpartially oxidized state, e.g., sulfone), nitrogen oxygen, hydroxyl,carbonyl, or covalent halogen, a restriction being that the hetero atomor group is not bonded directly to Z. The pendent linkage can range froma simple bond to branch of R₁ several atoms long connecting Z to thepolymer chain.

R₂, R₃ and R₄ can be defined independently as alkyl, alkenyl, aryl orcombinations thereof or can be hydrogen, except that they unlike R₁ arenot in the polymer chain. When R₂ is aryl including Z in a heterocyclicring and/or when Z is sulfur R₃ or R₄ may not exist.

Z is a cation such as those derived from nitrogen, phosphorous, orsulfur. In one preferred class not more than two of the three R groupscan be hydrogen. In another preferred class when R₂ is aryl and containsnitrogen, the aryl ring has at least one substitutent or contains oneother hetero atom or group.

X is an anion such as halide, nitrate, sulfate, hydroxide, etc.

n is an integer equal to the number of monomer units in the polymerrequired to give a polymer with a molecular weight in the range of about800-3,000,000.

m is an integer equal to the number of anions required to maintainneutrality.

A preferred molecular weight range is about 1,500-150,000.

The following are examples of the preferred polycationic polymer classeshaving repeating polymer units such as those illustrated below.

(1) where Z is sulfur, a sulfonium polymer ##STR7## and one example isderived from the monomer H₂ C═CHCO₂ CH₂ CH₂ S(CH₃)₂ Cl,poly-2-acryloxyethyldimethylsulfonium chloride; R₁ =2-acryloxyethyl, R₂=methyl, R₃ =methyl, R₄ =non-existent, and X=chloride;

The above formula and R groups show a polymer wherein the R groups arenot hydrogen.

(2) where Z is phosphorous, a phosphonium polymer ##STR8## and anexample monomer is ##STR9## glycidyltributylphosphonium chloride; R₁=glycidyl, R₂ =butyl, R₃ =butyl, R₄ =butyl, and X=chloride;

The above example shows a polymer wherein the cation Z is pendent andnot in the polymer chain and at least three of the R groups are thesame.

(3) where Z is nitrogen, quaternary ammonium polymers;

(3a) integral alkyl quaternary, example polymer: ##STR10##polydimethylethyleneammonium chloride, example polymer: ##STR11## thecondensation product of N,N,N',N'-tetramethylethylenediamine and1,4-dichlorobutane;

The above examples show polymers wherein the R groups are not hydrogen;wherein the cation Z is in the polymer chain and in the second exampleis also in one of the R groups; wherein two of the R groups are the sameand two of the R groups are different; and wherein at least two of the Rgroups are linear aliphatic radicals with not more than one and/or twodifferent radicals in the polymer chain.

(3b) Integral quaternary in cyclic ring, example polymer: ##STR12## thecondensation product of 4-chloropyridine; (3c) integral alkyl, arylquaternary, example polymer: ##STR13## the condensation product of1-(4-pyridyl)-3-chloropropane; another example polymer: ##STR14## thecondensation product of pyrazine and 1,2-ethylene dichloride; The aboveexamples show polymers with one or more cationic Z groups in the polymerchain and in an aromatic radical which is also in the polymer chain withtwo different R radicals which are also in the polymer chain. Thus, theexamples show heterocyclic aromatic and linear R groups which are in thepolymer chain.

(3d) Pendent alkyl quaternary, example polymer: ##STR15##polyvinyltrimethylammonium methylsulfate; The above example shows apolymer with a pendent cationic Z radical and pendent R groups which arethe same but different from the R group in the polymer chain; thus, Zand three of the R groups are not in the polymer chain.

(3e) Pendent quaternary on cyclic backbone, example polymer: ##STR16##The above example shows a polymer with aromatic and hetero radicals inthe polymer chain, a pendent cationic Z radical and three R groups whichare aliphatic and not hydrogen or not in the polymer chain.

(3f) Pendent quaternary on carbocyclic ring, example polymer: ##STR17##polyvinyl-4-benzyltrimethylammonium chloride; (3g) Pendent quaternarynitrogen on polymethacrylate backbone, example polymer: ##STR18##poly(3-methacryloxy-2-hydroxypropyltrimethylammonium chloride); Theabove example shows different R groups with one in the polymer chain andthree aliphatic R groups with one containing a cationic Z group andhetero atoms which are not in the polymer chain.

another example polymer: ##STR19##poly(acrylamido-3-propyltrimethylammonium chloride); The above exampleshows a polymer with pendent R groups and cations which are not in thepolymer chain, aliphatic R groups with one in the polymer chain, and apendent group containing hetero atoms and more than one Z group.

(3h) Quaternary nitrogen in pendent heterocyclic ring, example polymers:##STR20## poly-4-vinyl-N-methylpyridinium iodide; The above formulashows a polymer with a pendent hetero aromatic radical which is also acationic radical and they are not in the organic polycationic polymerchain.

(3i) Heterocyclic ring containing quaternary nitrogen, example polymers:##STR21## polymer of diallyldimethylammonium chloride. The aboveformulae show a pendent Z cation and pendent aliphatic R groups with atleast two of the R groups having the same number of carbon atoms andwith two R groups having the same number of carbon atoms and beinglinear aliphatic radicals in the polymer chain. The formulae also showheterocyclic aliphatic groups in the polymer chain which also havependent portions.

The above classes and subclasses of polycationic polymers can besubstantially linear or branched. Examples (3a), (3b) and (3c) can beconsidered substantially linear polymers. Examples (1), (2), (3d), (3e),(3f), (3g), (3h) and (3i) can be considered branched. These examplesshow branching through at least one organic radical such as examples(1), (2), (3d), (3e), (3f), (3g), (3h) and (3i) and through a cationradical such as example (3a). Also examples (3d), (3e), (3f), (3g), (3h)and (3i) can be considered to have branching through pendent cationradicals or hetero groups.

The following examples serve to illustrate various embodiments of theinvention and enable one skilled in the art to practice the invention.Parts, percentages, proportions and concentrations are by weight unlessindicated otherwise.

EXAMPLES Polycationic Polymer Test Procedure

Test Cell Composition:

The polycationic polymers were tested in a simulated formationcontaining sand, fine sediments, and clay. The test cell was packed byplacing a one-hole stopper in a glass tube. To prevent sand from fallingthrough, a screen consisting of wire gauze overlaid with a thin layer ofPyrex wool was placed on top of the bottom stopper. Next, to prevent thesand pack from plugging the screen, a layer of straight sand was packedon top of the stopper and screen. The next layer was the sand pack; thesand pack was the testing medium. It was packed in a damp condition sothat the sand, fines, and clay would adhere such that stratification ofthe pack was avoided. Finally, to protect the sand pack from particulatecontaminants, a layer of pure sand capped the lower two layers.

The sand pack consisted of 85% by weight pure Oklahoma No. 1 Sand(70-170 U.S. Mesh), 10% by weight silica (-270 U.S. Mesh), 5% by weightmontmorillonite (Wyoming bentonite-surface area about 750 m² /gram) and0.75 milliliters (ml) of brine water (enough for detectable dampness).

Test cell dimensions were: inside diameter of tube 2.32 centimeters;inside cross-sectional area of tube 4.23 cm² ; sand pack column height8.04 cm; tube volume (sand pack vicinity) 33.09^(cm).spsp.3 ; porosityabout 30%; and pure Oklahoma No. 1 sand column height (both top andbottom columns) 1.51 cm.

The test cell composition was maintained uniform from test to test. Theabove figures are the average of several cells on successive tests.

    ______________________________________                                        Averages of Some Test Cell Flow Rates                                         Temperature    Flow Rate                                                      °F.     ml/min                                                         ______________________________________                                         75             13.67*                                                        145            24.25                                                          200            41.50                                                          ______________________________________                                        Test Sequence or Procedure                                                    Step             Flowing Fluid                                                ______________________________________                                        1                Standard brine                                               2                Treatment solution                                           3                Standard brine                                               4                Fresh water                                                  5                15% HCl                                                      6                Fresh water                                                  7                Diesel oil                                                   8                Fresh water                                                  9                Diesel oil                                                   ______________________________________                                         *K = 140.3 md                                                            

The initial standard brine step was for calibrating the sand pack. Freshwater is tap water. Fresh water and deionized water are roughlyequivalent in their clay swelling properties, and they are the criticaltest of whether some step was effective in treating clay.

The 15% HCl step was to test the permanency of the clay treatingchemical in the presence of acid.

The diesel oil-fresh water-diesel oil steps had the purpose of testingthe permanence of the clay treating chemical in the presence of oil.Also, if the diesel oil rate is higher than the water rate the systemwas considered to be water wet.

    ______________________________________                                        Standard Brine Composition                                                    Salt           % by Weight                                                    ______________________________________                                        NaCl           7.5                                                            CaCl.sub.2     0.55                                                           MgCl.sub.2.6H.sub.2 O                                                                        0.42                                                           Water          91.53                                                          ______________________________________                                    

Pressure and Temperature

A pressure of 50 psig was maintained on the reservoir throughout allprocedure steps.

The reservoir had a heating jacket which maintained the desiredtemperature for the test fluids. A heating tape was used on the testcell.

Berea cores were tested in a Hassler sleeve apparatus with the core andreservoir heated to test temperature. The 2-inch long core rested on acushion of 40-60 sand (3/4" high) and was protected from unavoidabletrash by a buffer of 40-60 sand on top (3/4" high) with an uppermost capof Oklahoma No. 1 sand (1/4" high). These sand layers providedapproximately 2% of the cell resistivity.

    ______________________________________                                        Berea Sandstone Core Properties*                                                             Average                                                        ______________________________________                                        X-Ray Analysis                                                                Quartz           79.0%                                                        Dolomite         4.0%                                                         Kaolinite        11.0%                                                        Illite           3.7%                                                         Montmorillonite and                                                                            2.3%                                                         mixed layer clays                                                             Other Analysis                                                                Acid Solubility  2.8%                                                         Porosity         21.96%                                                       Permeability     208 md                                                       ______________________________________                                         *This is a sample of sixteen cores and is considered representative of th     sandstone block used for test cores.                                     

                  TABLE 1                                                         ______________________________________                                        Code for Clay Treating Chemicals                                              And Solutions Used in the Examples                                            Chemical                                                                      Code     Description                                                          ______________________________________                                        Control  The absence of any clay treating chemical.                           OHAl     Refers to hydroxy aluminum compounds which                                    have the following proportions in the examples:                               Al.sub.2 (OH).sub.5 Cl.                                              ZrOCl.sub.2                                                                            Zirconyl chloride analyzed to be ZrOCl.sub.2.8H.sub.2 O.             PEI      Polyethyleneimine, a polymer of aziridine.                           PDMDAA   Polydimethyldiallylammonium chloride.                                SB       Standard Brine.                                                      FW       Fresh water.                                                         TEPA     Tetraethylenepentamine                                               EDCA     Ethylene dichloride and ammonia condensate.                          EDCAM    Ethylene dichloride and ammonia condensate                                    quaternized with methyl chloride.                                    TETA     Triethylenetetraamine.                                               BDCTMDA  1,4-dichlorobutene condensate with                                            N,N,N',N'--tetramethylethylenediamine.                               DMAECH   Dimethylamine condensate with epichlorohydrin.                       BDMAECH  Dimethylamine condensate with epichlorohydrin                                 branched with ammonia.                                               DMABCD   Dimethylamine condensate with 1,4-                                            dichlorobutane.                                                      HXDA     1,6-hexanediamine.                                                   DEAPA    Diethylaminopropylamine.                                             TADATO   A triethanolamine/diethanolamine/tall oil                                     condensate.                                                          TADATOQ  TADATO quaternized with CH.sub.3 Cl.                                 HBEOTO   Hexanediamine production bottoms reacted with                                 ethylene oxide and esterified with tall oil and                               acidified with the hydrochloride.                                    PBMDMSA  Poly-2-butenylene-2-methylenedimethylsulfonium                                chloride.                                                            PAOEDMS  Polyacryloxy-2-ethylenedimethylsulfonium metho-                               sulfate                                                              PEOMTBP  Polyethylene-2-oxy-1-methylenetributyl-                                       phosphonium chloride.                                                ______________________________________                                    

                                      TABLE 2                                     __________________________________________________________________________    Clay Treatment Flow Tests at 75° F.                                    Example No.                                                                              1    2    3     4     5     6     7     8     9                    __________________________________________________________________________    Treatment Solution                                                            Chemical or Polymer                                                                      Control                                                                            Control                                                                            PDMDAA                                                                              PDMDAA                                                                              PDMDAA                                                                              PDMDAA                                                                              PDMDAA                                                                              PDMDAA                                                                              PDMDAA               Molecular Weight.sup.b                                                                   NA   NA   37,000                                                                              37,000                                                                              37,000                                                                              37,000                                                                              37,000                                                                              50,000                                                                              75,000               Concentration, %                                                                         0    0    4     2     0.4   0.4   2     2     2                    Solvent    SB   SB   FW    FW    FW    SB    SB    SB    SB                   Calibration                                                                   Standard brine,                                                               ml/min.    14.6 13.4 12.3  13.4  15.2  14.6  14.4  12.8  15.2                 Flow Tests, % of                                                              Calibration                                                                   Solution                                                                              ml                                                                    Standard brine                                                                        500                                                                              100.0                                                                              100.0                                                                              100.0 100.0 100.0 100.0 100.0 100.0 100.0                Treatment                                                                             300                                                                              --   --   17.1  23.1  3.5.sup.a                                                                           80.8  49.3  39.8  31.5                 solution                                                                      Standard brine                                                                        500                                                                              --   --   99.2  82.1  5.0.sup.a                                                                           101.4 102.8 100.0 92.1                 Fresh Water                                                                           500                                                                              1.0.sup.a                                                                          --   99.2  88.1  --    68.5  104.2 100.0 81.6                 15% HCl 400                                                                              --   70.1 86.1  73.1  --    71.2  73.6  79.7  82.9                 Fresh Water                                                                           500                                                                              --   0.6  94.3  85.1  --    61.6  91.7  85.9  68.4                 __________________________________________________________________________     .sup.a Flow was terminated before the full volume indicated was delivered     .sup.b The molecular weights are believed to be about ±10%.           

                                      TABLE 3                                     __________________________________________________________________________    Temperature and Solvent Variations with Organic Polycationic Polymers         Example No.  10   11    12    13    14     15     16     17                   Test Temperature, °F.                                                               145°                                                                        145°                                                                         145°                                                                         200°                                                                         145°                                                                          200°                                                                          145°                                                                          145°          __________________________________________________________________________    Treatment Solution                                                            Chemical or Polymer                                                                        Control                                                                            PDMDAA                                                                              PDMDAA                                                                              PDMDAA                                                                              PDMDAA PDMDAA PEI    PDMDAA               Molecular Weight.sup.b                                                                     NA   37,000                                                                              37,000                                                                              37,000                                                                              37,000 37,000 20,000 37,000               Concentration, %                                                                           0    2     0.4   0.4   0.4    0.4    0.1    0.4                  Solvent      SB   SB    SB    SB    15% HCl                                                                              15% HCl                                                                              15% HCl                                                                              3% CaCl.sub.2        Calibration                                                                   Standard brine, ml/min.                                                                    23   26    32    38    18     45     19.6   29.0                 Flow Tests, % of                                                              Calibration                                                                   Solution  ml                                                                  Standard brine                                                                          500                                                                              100.0                                                                              100.0 100.0 100.0 100.0  100.0  100.0  100.0                Treatment solution                                                                      300                                                                              --   50.0  90.6  96.1  63.9   62.6   98.0   65.5                 Standard Brine                                                                          500                                                                              --   111.5 106.0 135.5 136.1  113.3  132.7  75.2                 Fresh water                                                                             500                                                                              1.1.sup.c                                                                          126.9 111.9 147.0 130.0  120.0  167.3  82.8                 15% HCl   400                                                                              --   40.0  93.8.sup.a                                                                          39.5  --     --     --     20.0                 Fresh water                                                                             500                                                                              --   100.0 156.3 131.5 --     --     --     79.3                 __________________________________________________________________________     .sup.a A solution of 3% HF and 12% HCl was substituted for 15% HCl.           .sup.b The molecular weights are believed to be within ±10%. The PDMDA     is number average of molecular weight; PEI is unspecified.                    .sup.c Flow testing was discontinued after 100 ml of fresh water due to       low flow rate.                                                           

                                      TABLE 4                                     __________________________________________________________________________    Organic Polycationic Polymers Consisting Generally of                         Alternating Ethylene and Amine Groups                                         __________________________________________________________________________    Example No.  18  10   20  21    22   23                                       __________________________________________________________________________    Treatment Solution                                                            Chemical or Polymer                                                                        EDCA                                                                              EDCA EDCA                                                                              EDCAM EDCAM                                                                              PEI                                      Molecular Weight                                                                           7,500.sup.a                                                                       25,000.sup.a                                                                       1,500.sup.b                                                                       2,000.sup.b                                                                         20,000.sup.c                                  Concentration, %                                                                           0.25                                                                              0.28 0.36                                                                              0.25  0.25 0.1                                      Solvent      SB  SB   SB  SB    SB   SB                                       Solvent pH   4   4    4   4     7    4                                        Calibration                                                                   Standard Brine, ml/min.                                                                    23.2                                                                              20.8 23.0                                                                              17.2  17.6 23.6                                     Flow Tests.sup.d, % of                                                        Calibration                                                                   Solution  ml                                                                  Standard Brine                                                                          500                                                                              100.0                                                                             100.0                                                                              100.0                                                                             100.0 100.0                                                                              100.0                                    Treatment Solution                                                                      300                                                                              80.2                                                                              59.6 108.7                                                                             110.5 110.8                                                                              101.7                                    Standard Brine                                                                          500                                                                              90.5                                                                              56.7 104.3                                                                             98.8  102.3                                                                              100.0                                    Fresh Water                                                                             500                                                                              100.9                                                                             46.2 139.1                                                                             130.8 130.7                                                                              35.6                                     15% HCl   400                                                                              56.0                                                                              31.3 50.0                                                                              60.5  82.4 14.8                                     Fresh Water                                                                             500                                                                              120.7                                                                             74.5 156.5                                                                             157.0 210.2                                                                              114.4                                    __________________________________________________________________________    Example No.  24  25   26  27  28   29  30                                     __________________________________________________________________________    Treatment Solution                                                            Chemical or Polymer                                                                        PEI PEI  PEI PEI PEI  TEPA                                                                              TETA                                   Molecular Weight                                                                           20,000.sup.c                                                                      20,000.sup.c                                                                       300.sup.c                                                                         1,200.sup.c                                                                       100,000.sup.c                                                                      189 146                                    Concentration, %                                                                           1.0 1.0  0.3 0.3 1.0  1.0 1.0                                    Solvent      SB  15% HCl                                                                            SB  SB  15% HCl                                                                            SB  SB                                     Solvent pH   4   --   4   4   --   4   4                                      Calibration                                                                   Standard Brine, ml/min.                                                                    21.4                                                                              25.4 21.4                                                                              23.5                                                                              21.9 22.6                                                                              26.2                                   Flow Tests.sup.d, % of                                                        Calibration                                                                   Solution  ml                                                                  Standard Brine                                                                          500                                                                              100.0                                                                             100.0                                                                              100.0                                                                             100.0                                                                             100.0                                                                              100.0                                                                             100.0                                  Treatment Solution                                                                      300                                                                              7.5 51.2 123.8                                                                             102.1                                                                             11.4 115.0                                                                             139.8                                  Standard Brine                                                                          500                                                                              6.1 70.0 126.2                                                                             110.6                                                                             25.1 95.1                                                                              114.5                                  Fresh Water                                                                             500                                                                              --  94.5 146.7                                                                             139.0                                                                             1.1  2.8.sup.d                                                                         0.4                                    15% HCl   400                                                                              15.0                                                                              --   58.9                                                                              22.6                                                                              --   --  --                                     Fresh Water                                                                             500                                                                              --  --   3.9 4.7 --   --  --                                     __________________________________________________________________________     .sup.a This molecular weight is approximately ±2,500 with chloride         counter ion not included.                                                     .sup.b This molecular weight is approximately ±500 with chloride           counter ion not included.                                                     .sup.c The spread of this molecular weight is unknown.                        .sup.d These tests were at 145° F.                                

                                      TABLE 5                                     __________________________________________________________________________    Miscellaneous Organic Polycationic Polymers                                   __________________________________________________________________________    Example No.    31      32    33     34    35                                  __________________________________________________________________________    Treatment Solution                                                            Chemical or Polymer                                                                          BDCTMDA DMAECH                                                                              DMAECH DMAECH                                                                              DMAECH                              Molecular Weight                                                                             1,500   1,750.sup.a                                                                         7,500.sup.b                                                                          7,500.sup.b                                                                         7,500.sup.b                         Concentration, %                                                                             0.5     0.37  0.37   0.185 0.037                               Solvent        SB      SB    SB     SB    SB                                  Solvent pH     4       4     4      4     4                                   Calibration                                                                   Standard Brine, ml/min.                                                                      23.6    21.2  19.4   22.2  30.3                                __________________________________________________________________________    Flow Tests.sup.c, % of Calibration                                            Solution   ml                                                                 Standard Brine                                                                           500 100.0   100.0 100.0  100.0 100.0                               Treatment Solution                                                                       300 114.4   109.4 108.8  117.6 113.2                               Standard Brine                                                                           500 111.9   121.2 134.5  131.1 122.1                               Fresh Water                                                                              500 150.4   159.4 182.0  155.4 6.9                                 15% HCl    400 74.2    44.8  93.8   82.4  --                                  Fresh Water                                                                              500 154.3   184.0 156.2  128.8 --                                  __________________________________________________________________________    Example No.    36    37    38     39    40  41                                __________________________________________________________________________    Treatment Solution                                                            Chemical or Polymer                                                                          DMAECH                                                                              DMAECH                                                                              BDMAECH                                                                              DMABDC                                                                              HXDA                                                                              DEAPA                             Molecular Weight                                                                             1,750.sup.a                                                                         7,500.sup.b                                                                         17,500.sup.b                                                                         1,500 116 130                               Concentration, %                                                                             0.37  0.37  0.37   0.39  1.0 1.0                               Solvent        5% HCl                                                                              5% HCl                                                                              SB     SB    SB  SB                                Solvent pH     --    --    4      4     4   4                                 Calibration                                                                   Standard Brine, ml/min.                                                                      26.3  35.3  21.4   23.1  22.2                                                                              23.0                              __________________________________________________________________________    Flow Tests.sup.c, % of Calibration                                            Solution   ml                                                                 Standard Brine                                                                           500 100.0 100.0 100.0  100.0 100.0                                                                             100.0                             Treatment Solution                                                                       300 76.0  103.1 79.9   108.2 122.5                                                                             114.8                             Standard Brine                                                                           500 85.2  106.2 130.7  116.9 104.9                                                                             104.4                             Fresh Water                                                                              500 108.7 124.9 112.1  124.2 2.6 0.4                               15% HCl    400 10.9  85.5  34.6   51.5  --  --                                Fresh Water                                                                              500 117.5 113.3 112.1  160.2 --  --                                __________________________________________________________________________     .sup.a The molecular weight spread is about ±250.                          .sup.b The molecular weight spread is about ±2,500.                        .sup.c These tests were at 145° F.                                

                  TABLE 6                                                         ______________________________________                                        Clay Treatment with Inorganic Cationic Polymers at 75° F.              Example No.    42         43       44                                         ______________________________________                                        Treatment Solution                                                            Chemical or Polymer                                                                          Control    HOAl     ZrOCl.sub.2                                Molecular Weight                                                                             NA         --.sup.a --.sup.a                                   Concentration, %                                                                             0          2.5      1.2                                        Solvent        3% CaCl.sub.2                                                                            2% KCl   2% KCl                                     Calibration                                                                   Standard Brine, ml/min.                                                                      11.9       15.2     15.8                                       ______________________________________                                        Flow Tests                                                                    Solution    ml                                                                Standard Brine                                                                            500    100.0      100.0  100.0                                    3% CaCl.sub.2                                                                             300    74.0       83.3   68.4                                     Deionized Water                                                                           300    60.0       61.8   41.1                                     Treatment Solution                                                                        100    --         42.8   34.8                                     Overflush   100    --         43.4   29.7                                     Cure Time   NA     --         --.sup.b                                                                             --                                       3% NaCl     300    38.0       40.7   31.6                                     Deionized Water                                                                           300    1.1        44.1   31.6                                     15% HCl     300    --         27.6   25.3                                     Deionized Water                                                                           300    --         1.0    0.6                                      ______________________________________                                         .sup.a Not determined.                                                        .sup.b 18 hours.                                                         

                  TABLE 7                                                         ______________________________________                                        Organic Polycationic Polymers As Clay -Control Agent in a Carbonaceous        Formation                                                                     ______________________________________                                        Test Sand Composition                                                                          Percent By Weight                                            Material           Pack A   Pack B                                            ______________________________________                                        70-170 Mesh Sand   75       0                                                 70-170 Mesh Marble Chips                                                                         10       85                                                Through 270 Mesh Silica                                                                          10       10                                                Montmorillonite     5       5                                                 ______________________________________                                        Example No.     45       46        47                                         ______________________________________                                        Treatment Solution                                                            Chemical or Polymer                                                                           Control  PDMDAA    PDMDAA                                     Molecular Weight                                                                              NA       37,000    37,000                                     Concentration, %                                                                              NA       0.4       0.4                                        Solvent         FW       SB        SB                                         Calibration                                                                   Pack Used       A        A         B                                          Standard Brine, ml/min.                                                                       15.0     13.6      3.2                                        ______________________________________                                        Flow Tests, % of Calibration                                                  Solution    ml                                                                Standard Brine                                                                            500     100.0    100.0   100.0                                    Treatment Solution                                                                        300     --       105.9   93.8                                     Standard Brine                                                                            500     --       122.1   96.9                                     Fresh Water 500     2.8      125.0   109.4                                    15% HCl     400     --       76.5    --                                       Fresh Water 500     --       169.1   --                                       ______________________________________                                    

                                      TABLE 8                                     __________________________________________________________________________    Water Wetting Affected by Clay Stabilization Agents                           Example No.   48    49     50    51   52                                      __________________________________________________________________________    Extension of Example                                                                        32    38     33    14   16                                      Treatment Solution                                                            Chemical or Polymer                                                                         DMAECH                                                                              BDMAECH                                                                              DMAECH                                                                              PDMAA                                                                              PEI                                     Concentration, %                                                                            0.37  0.37   0.37  0.4  0.1                                     Solvent       SB    SB     SB    15% HCl                                                                            15% HCl                                 __________________________________________________________________________    Flow Tests, -% of Calibration                                                 In Original Example                                                           Fluid      ml                                                                 Diesel Oil 500                                                                              139.2 68.2   72.2  94.4 84.1                                    Fresh Water                                                                              500                                                                              24.1  16.8   24.2  13.3 83.7                                    Diesel Oil 500                                                                              132.1 61.7   72.2  85.5 92.9                                    __________________________________________________________________________

                  TABLE 8A                                                        ______________________________________                                        Clay Treatments With Organic Polycationic                                     Polymers Containing Oxygen Linkages                                           Example No.    52A       52B       52C                                        ______________________________________                                        Treatment Solution                                                            Chemical or Polymer                                                                          TADATO    TADATO    HBEOTO                                     Concentration, %                                                                             0.86      0.7       0.68                                       Solvent        SB        SB        SB                                         Calibration                                                                   Standard Brine, ml/min.                                                                      23.0      27.0      19.77                                      ______________________________________                                        Flow Tests, % of                                                              Calibration                                                                   Solution    ml                                                                Standard Brine                                                                            500    100.0     100.0   100.0                                    Treatment Solution                                                                        100    89.1      81.5    56.9                                     Standard Brine                                                                            500    95.7      98.5    93.4                                     Fresh Water 500    115.2     136.3   136.0                                    15% HCl     400    46.1      33.7    39.1                                     Fresh Water 500    140.4     118.5   181.7                                    Diesel Oil  500    110.9     84.4    97.5                                     Fresh Water 500    33.9      26.7    86.3                                     Diesel Oil  500    113.5     86.7    86.8                                     ______________________________________                                    

                  TABLE 8B                                                        ______________________________________                                        Clay Treatment With Cations Other Than Nitrogen                               Example No.  52D        52E        52F                                        ______________________________________                                        Treatment Solution                                                            Chemical or Polymer                                                                        PBMDMSC     PAOEDMS   PEOMTBP                                    Concentration %                                                                            1.0         1.0       1.0                                        Solvent      SB          SB        SB                                         Calibration                                                                   Standard Brine,                                                               ml/min       24.0        23.2      26.9                                       ______________________________________                                        Flow Tests,                                                                   % of Calibration                                                              Solution  ml                                                                  Standard Brine                                                                          500    100.0      100.0    100.0                                    Treatment                                                                     Solution  100    76.6       75.8     59.0                                     Standard Brine                                                                          500    95.3       95.7     93.2                                     Fresh Water                                                                             500    128.3      131.4    141.3                                    15% HCl   400    39.6       38.4     33.4                                     Fresh Water                                                                             500    146.7      126.4    178.9                                    Diesel Oil                                                                              500    110.8      100.2    97.6                                     Fresh Water                                                                             500    32.5       48.6     60.3                                     Diesel Oil                                                                              500    111.1      95.7     97.6                                     ______________________________________                                    

                                      TABLE 9                                     __________________________________________________________________________    Clay Stabilization Tests in Berea Cores                                       Pressure; 50 psig Temperature: 145° F.                                 Example No.    53   54    55   56    57   58   59  60    61                   __________________________________________________________________________    Treatment Solution                                                            Chemical or Polymer                                                                          None None  ZrOCl.sub.2                                                                        ZrOCl.sub.2                                                                         ZrOCl.sub.2                                                                        ZrOCl.sub.2                                                                        OHAl                                                                              PDMDAA                                                                              PDMDAA               Concentration, %          1.2  1.2    1.2 1.2  2.5 0.4   0.4                  Solvent        Control                                                                            Control                                                                             2% KCl                                                                             2% KCl                                                                              4% KCl                                                                             3% HCl                                                                             FW  SB    SB                   Calibration                                                                   Standard Brine, ml/min.                                                                      14.0 11.8  27.0 24.8   10.6                                                                              17.2 16.0                                                                              19.0  8.3                  __________________________________________________________________________    Flow Tests, % of Calibration                                                  Solution   ml                                                                 Standard Brine                                                                           300 100.0                                                                              100.0 100.0                                                                              100.0 100.0                                                                              100.0                                                                              100.0                                                                             100.0 100.0                Treatment Solution                                                                       200 --   --    39.3 145.2.sup.b                                                                         --.sup.c,d                                                                         50.0 87.5                                                                              90.5  85.5                 Standard Brine                                                                           300 --   --    3.7  28.2  --   55.6 62.5.sup.e                                                                        105.3 96.4                 Fresh Water                                                                              300 0.5  --    48.0 19.8  --   104.7                                                                              58.7                                                                              121.1 108.4                15% HCl    250 --   35.6  --   46.4  --   --   4.3 16.3  38.6                 Fresh Water                                                                              300 --   211.7.sup.a                                                                         --   100.8 --   --   215.6                                                                             204.2 596.4                Diesel Oil 300 --   --    --   --    --   --   112.5                                                                             60.5  255.4                Fresh Water                                                                              300 --   52.5  --   --    --   --   35.0                                                                              13.2  104.8                Diesel Oil 300 --   --    --   --    --   --   106.3                                                                             33.7  224.1                __________________________________________________________________________     .sup.a Standard brine substituted for fresh water in this flow test step      so that the increase in permeability by acidizing could be measured.          .sup.b The treatment solution was preceded by 100 ml of 5% HCl.               .sup.c The treatment solution was preceded by 100 ml of 4% KCl.               .sup.d There was no detectable flow rate after injecting 85 ml of             treatment solution.                                                           .sup.e The treatment solution was followed by an overflush of 100 ml of 1     KCl.                                                                     

                                      TABLE 10                                    __________________________________________________________________________    Remedial Treatments to Correct Previous Damage to Permeability of Berea       Cores                                                                         __________________________________________________________________________    Example No. 62          63          64                                        __________________________________________________________________________    Treatment Solution                                                            Chemical or Polymer                                                                       Control     Control     Control                                   Concentration, %                                                                          --          --          --                                        Solvent     None        SB          5% HCl                                    __________________________________________________________________________    Fluid Injected                                                                            Vol.                                                                              (D) Rate                                                                              Vol.                                                                              (D) Rate                                                                              Vol.                                                                              (D) Rate                              __________________________________________________________________________    Standard Brine                                                                            480 (F) 22.6                                                                              390 (F) 15.0                                                                              510 (F) 26.0                              Deionized Water                                                                            76 (F)  3.6                                                                              23  (F) 0.5 155 (F) 0.6                               Treatment Solution                                                                        --  (R) --  98  (R) 1.42                                                                              102 (R) 2.4                               Deionized Water                                                                           --  (F) --  36  (F) 0.7 237 (F) 33.0                              Deionized Water                                                                           --  (F) --  --  (F) --  1021                                                                              (F) 29.0                              Deionized Water                                                                           --  (F) --  --  (F) --  2801                                                                              (F) 15.2                              __________________________________________________________________________    Example No. 65       66       67       68                                     __________________________________________________________________________    Treatment Solution                                                            Chemical or Polymer                                                                       PMDAA    ZrOCl.sub.2                                                                            PMDAA    ZrOCl.sub.2                            Concentration, %                                                                          0.4      2.2      0.4      2.2                                    Solvent     SB       SB       5% HCl   5% HCl                                 __________________________________________________________________________    Fluid Injected                                                                            Vol.                                                                             (D)                                                                              Rate                                                                             Vol.                                                                             (D)                                                                              Rate                                                                             Vol.                                                                             (D)                                                                              Rate                                                                             Vol.                                                                             (D)                                                                              Rate                             __________________________________________________________________________    Standard Brine                                                                            300                                                                              (F)                                                                              10.6                                                                             390                                                                              (F)                                                                              17.7                                                                             450                                                                              (F)                                                                              13.4                                                                             420                                                                              (F)                                                                              18.0                             Deionized Water                                                                           96 (F)                                                                              4.4                                                                              10 (F)                                                                              0.2                                                                              348                                                                              (F)                                                                              0.82                                                                             7  (F)                                                                              0.2                              Treatment Solution                                                                        98 (R)                                                                              3.5                                                                              28 (R)                                                                              0.03                                                                             97 (R)                                                                              4.3                                                                              92 (R)                                                                              1.9                              Deionized Water                                                                           30 (F)                                                                              8.1                                                                              7  (F)                                                                              0.02                                                                             728                                                                              (F)                                                                              13.0                                                                             234                                                                              (F)                                                                              29.0                             Deionized Water                                                                           450                                                                              (F)                                                                              11.4                                                                             -- (F)                                                                              -- 1505                                                                             (F)                                                                              25.0                                                                             1008                                                                             (F)                                                                              12.0                             Deionized Water                                                                           600                                                                              (F)                                                                              11.4                                                                             -- (F)                                                                              -- 2717                                                                             (F)                                                                              25.0                                                                             2705                                                                             (F)                                                                              4.0                              __________________________________________________________________________     Control = Blank or no agent.                                                  -- = Not run.                                                                 Vol = Flow rate in ml/min.                                                    (D) = Direction of flow.                                                      (F) = Flow in "forward" direction, i.e., original direction.                  (R) = Flow in reverse direction.                                              Pressure  50 psig.                                                            Temperature = 145° F.                                             

EXAMPLE NO. 69

A sample of Milk River formation from a well in the vicinity of MedicineHat, Alberta, Canada was placed in fresh water. The sample begain toseparate at the laminations in ten seconds. In one minute sloughing ofthe edges was observed; in five minutes, the sample had disintegratedinto a non-cohesive mound.

EXAMPLE NO. 70

A sample of Milk River formation was placed in fresh water containing0.8% PDMDAA. There was no observable decomposition of the sample. In 24hours, there was a trace of separation of the laminations; in six monthsno other evidence of disintegration was seen; the sample had nosloughing and the jagged edges of the laminations at the sample edgeswere still quite distinct.

Examples 69 and 70 show that PDMDAA can prevent the cave-ins of wellbores penetrating so-called "heaving shales" or "gumbo shales." Thesewater sensitive formations are not uncommon and cause problems duringdrilling by caving into the well bore and seizing the the drill pipe.Besides stuck drill pipe problems, water sensitive formations can causeout-of-gauge holes, and problems in placing casing when drilling iscomplete. Examples of water sensitive formations that give problems indrilling, running casing, or cementing wells are Milk River shale,Canada; Atoka sand, East Oklahoma; Glenrose shale, South Louisiana; andAnawhac shale, South Texas.

                                      TABLE 11                                    __________________________________________________________________________    Treatments With Organic Polycationic Polymer                                  In A Polar Solvent                                                            Example No.   71    72    73     74                                           __________________________________________________________________________    Treatment Solution                                                            Chemical or Polymer                                                                         Control                                                                             PDMDAA                                                                              DMAECH DMAECH                                       Molecular Weight                                                                            0     37,000.sup.a                                                                        1750.sup.b                                                                           7500.sup.c                                   Concentration, %                                                                            0     0.4   0.37   0.37                                         Solvent       Methanol                                                                            Methanol                                                                            Methanol                                                                             Methanol                                     Calibration                                                                   Standard Brine, ml/min.                                                                     25.6  25.0  24.2   22.9                                         __________________________________________________________________________    Flow Tests, % of Calibration                                                  Solution   ml                                                                 Standard Brine                                                                           400                                                                              100.0 100.0 100.0  100.0                                        Treatment Solution                                                                       100                                                                              107.0 142.8 99.6   110.5                                        Standard Brine                                                                           400                                                                              77.7  93.2  123.6  91.7                                         Fresh Water                                                                              400                                                                              11.7  115.6 159.1  138.0                                        15% HCl    400                                                                              --    56.8  57.0   41.9                                         Fresh Water                                                                              500                                                                              --    95.6  120.7  130.1                                        __________________________________________________________________________     .sup.a -- ±3,700                                                           .sup.b -- ±250                                                             .sup.c -- ±2,500                                                      

EXAMPLE 75

In the Bantry Field near Brooks, Alberta, Canada, the Milk Riverformation gave much trouble. The heaving formation caused irregular holesize which was bad for proper cementing of casing in the hole. Inaddition, it was difficult to get logging tools through the Milk Riverformation in order to test for oil and/or gas.

Seven wells were drilled using DMAECH. The drilling fluid sump systemwas arranged to permit "clear water" drilling. After the top of the MilkRiver interval was approached at approximately 1000 feet deep, DMAECHwas metered into the pump suction throughout the drilling of theremainder of the zone. It took only an average of six hours to reach thebase of the producing zone at approximately 1700 feet.

The caliper log showed the hole to be smooth-walled "like a gun barrel."Logging tools were lowered through the zone with ease. The wells werecased with no problems during cementing. After well completion by casingperforation, the wells were stimulated by fracturing using one gallon of40% DMAECH solution per 1000 gallons of fracturing fluid throughout thetreatment.

The wells stabilized producing an average 300,000 cubic feet of gas perday against a pressure of 240 psig. This deliverability is, on theaverage, threefold better than neighboring wells that used potassiumchloride instead of DMAECH.

EXAMPLE 76 PDMDAA Treatment Vs. 10% KCl Survey of Production Results inWest Virginia

In a survey of production from wells treated in late 1976 and early1977, PDMAA has proven to be a far superior agent for use in a local,fresh water sensitive formation, the Big Injun sand. The nine wells werechosen at random, revolving around the first PDMDAA treatment in 1976.All wells treated were near the center of the Big Injun Field, nearLizemores, Clay County, W.Va. The five wells treated with PDMDAA andfour 1% KCl wells all had the same basic formation criteria:

12-15% average porosity

1-5 millidarcy average permeability

20 feet of net pay

Average depth--2500-2600 feet

All wells were treated down 41/2" casing at 20-25 barrels per minute atapproximately 1900-2300 PSI with the following materials:

Cellulose derived gelling agent--20 lbs/1000 gallons

Antifluid loss agent--20 lbs/1000 gallons

Citric acid--10 lbs/1000 gallons

Cationic non-emulsifying agent--1 gal./1000 gallons

500 sacks--20-40 sand

200 sacks--10-20 sand

500 gallons--HCl (15%) acid

900-1000 barrels of sand laden fluid

The only difference was that five wells were treated with 40% PDMDAAsolution at 1/2 gallon per 1000 gallons throughout the job and four weretreated with 1% KCl.

Other than the obvious benefit of a savings of about $500.00 per well,the use of PDMDAA supported the following conclusions:

1. The wells cleaned up faster.

2. The open flow potential for an average well treated with PDMDAA wasfound to be 31% higher than a similar well treated with 1% KCl.

3. The average first year production of the PDMDAA treated wells was 82%higher than those treated with 1% KCl.

4. Last and more important, taking into consideration the higher openflow values of the PDMDAA treated wells, the wells treated with PDMDAAproduced at a higher percentage of their open flow values: 13% forPDMDAA versus 9% for 1% KCl.

The operator estimated that the wells treated with PDMDAA generated$42,000 more revenue than the KCl wells.

Table 1 gives the code for clay treating chemicals and solutions used inthe examples.

Table 2, Examples 1-9, are room temperature tests of various molecularweights of polydiallydimethylammonium chloride. The first two examplesprovide controls or specimen of the results in the absence of treatmentwith clay controlling chemicals. The result of Example 2 is interestingbecause hydrochloric acid is often used as a clay control chemical.Examples 3 and 4 provide instances of using fresh water as the carryingfluid for the clay treating chemical. Examples 5 and 6 indicate that atlower concentrations of clay control chemicals may require salt in thecarrying fluid (Treatment Solution). Perhaps there is a short reactiontime before the clay treating chemical can attach to the clay and duringthis time interval, salinity is required to hold the clay in check.Examples 7, 8 and 9 may indicate that the optimum molecular weight ispassed because the protection afforded by thepolydiallyldimethylammonium chloride declines with molecular weight.

Table 3, Examples 10-17, illustrate the temperature and solventvariations with organic polycationic polymers.

Example 10 shows that the sand pack can be expected to plug when freshwater is introduced without preliminary treatment with a claystabilization agent. The primary difference between Example 10 andExample 1 is temperature.

Examples 10 through 17 provide a variety of temperatures and solventsfor PDMDAA as contrasted with Examples 1 through 9. As indicated inFootnote a for Example 12, the increase in flow rate for the fresh waterphase after acid may be due to dissolving of clay and fines by thehydrofluoric acid rather than the sole effect of PDMDAA. The use oforganic polycationic polymers in conjunction with HF solutions is animportant application.

Table 4, Examples No. 18-30, illustrate organic polycationic polymersconsisting generally of alternating ethylene and amine groups.

The characteristic shared by the polymers is the structure --CH₂ --CH₂--N. However, variations on the nitrogen atom are several and may occurin the same polymer molecule, i.e: ##STR22##

Supposedly EDCA and PEI are the same polymer arrived at by differentsynthesis but their behavior is different. Compare Example 20 withExample 27. Similar molecular weights and concentrations give similarresults until the last flow rate phase (fresh water after 15% HCl).Evidently PEI is washed off by HCl.

With Examples 18, 19 and 20, it would appear that there is an optimummolecular weight with Example 19 being somewhat too high.

The pH difference between Examples 21 and 22 indicates that EDCAM is alittle better at a neutral pH. Since EDCAM is quaternized, pH should notalter the nitrogen atoms in this polymer.

The remaining compound is Table 4 has primary, secondary and tertiaryamines present and some have a percentage of quaternary amines.Adjusting the pH to 4 essentially transforms the primary, secondary andtertiary amines to the ammonium state (amine hydrochloride).

Examples 29 and 30 are preferred embodiments of Brown U.S. Pat. No.2,761,843. Example 30 is in claims 6 and 11 of U.S. Pat. No. 2,761,843and both are in the table at column 6 of Brown U.S. Pat. No. 2,761,843.These two compounds fail to prevent plugging of the test cell sand andclay pack with fresh water. It is believed that the molecular weights ofTEPA and TETA are too low and that cation exchange takes place rapidlywhen the standard brine is passed through. This removal of the amineoligomers allows the clay to swell when fresh water passes through.

The flow tests in this invention more closely resemble the actions of aproducing geological formation that do the washing techniques of BrownU.S. Pat. No. 2,761,848, column 5, lines 25-74. In this invention, thetechnique used attempts to simulate an actual well condition; that is:

Step 1--Calibration with brine simulates the flow of formation fluid.

Step 2--Treatment with a clay control agent simulates treatment of thewell.

Step 3--Brine flow simulates placing the well back on production. Thisstep checks to see if formation brine will remove the clay controlagent. Monomeric clay control agents such as potassium, ammonium orcalcium ion are removed in this step.

Step 4--Fresh water flow simulates introduction of a foreign water intothe formation.

Step 5--15% HCl flow simulates acidizing treatment of the formation. Ifit is advantageous later in the life of the well to clean it up or tostimulate the well with acid, it is an advantage to have the claycontrol agent resistant to removal by cation exchange with hydrogen ion.

Step 6--Fresh water flow simulates introduction of foreign water intothe fomation. This checks the resistance of the clay control agent toacid.

The Brown technique is more appropriate to lake or pond clarificationand sewage treatment where many polycationic compounds are used, than totreating oil or water wells.

Table 5, Examples 31-41, contains examples of organic polycationicpolymers with different constitution from those in Tables 2, 3 and 4.Examples 31 and 39 have an unsaturation in the carbon linkage. Examples32 through 38 have a hydroxyl group on the carbon linkage.

With the exception of Examples 40 and 41, these are effective claycontrol agents. Examples 33, 34 and 38 show concentration effects withExample 38 having an inadequate concentration.

Table 6, Examples 42-44, contains inorganic clay control agents.Examples 43 and 44 contain inorganic polycationic polymers according tothe literature.

Example 42 serves a dual purpose. It is the control for Examples 43 and44 and it is also an example of removal of a monomeric cationic claycontrol agent with a brine.

Examples 43 and 44 show that that the inorganic polycationic polymerslack resistance to acid so if a well operator desired to acidize hiswell perhaps a year after treating with an inorganic clay control agent,it would be advisable to re-treat the clay in the well after acidizing.

Table 7, Examples 45-47, provides examples of how an organicpolycationic polymer can function as a clay control agent in acarbonaceous formation. The inorganic agents such as hydroxy aluminum(HOAl) are not recommended for formation containing more than about 5%carbonate material because reaction of the acid (low pH) salt with thecarbonate will convert the hydroxy aluminum chloride to the ineffectivealuminum hydroxide. Furthermore, aluminum hydroxide has the distinctpossibility of acting as a plugging precipitate in the formationcapillaries. The metallic salts of Veley et al. U.S. Pat. No. 3,382,924are also acidic in pH and tend to be incompatible with carbonatecomponents of a formation.

Example 45 shows that a formation containing carbonate and clay can haveits fluid production capacity damaged. On the other hand, Example 46indicates that an organic polycationic polymer can prevent loss ofpermeability in a clayey carbonate containing formation. The increase inpermeability after acid in Example 46 is probably due to removal ofcarbonate by acid.

Since the marble chips were angular in particle shape, they producelower permeability than the sand they replaced, although the particlesof each closely fit the same mesh size. Example 47 evidently exhibits alow flow rate in calibration because of this. In Example 47 an organicpolycationic polymer demonstrates that it is capable of preventing lossof permeability due to swelling and/or migration of included fines andclay in the formation even when carbonate is the major component of theformation.

Table 8, Examples 48-52, illustrates that polycationic polymers do notoil wet the formation.

Since cationic surfactants can treat clays and prevent clay and finesswelling and/or migration, but are subject to the objection that theyare causing the formation to be oil wet, it seemed prudent to check theorganic polycationic polymers for their ability to oil wet or water weta formation. Certain examples have additional flow rate phases added tothe test procedure, hydrocarbon, fresh water and hydrocarbon. Diesel oilwas a convenient hydrocarbon to use. Examples 48 through 51 show apattern of high diesel oil flow and low water flow. This is a goodindication for water wetness. Example 52 indicates a "neutral"condition, not particularly oil or water wet.

The encouraging things about examples 48 through 52 are that the dieseloil had a viscosity of about 2.5 times that of the fresh water and yethigh diesel oil flow rate resulted. Also, when two phases or fluids arepresent in the same capillary flow system, there exists a conditioncalled "relative permeability" whereby neither flow rate is as high aswhen only a single phase or fluid is present. In fact, the sum of therelative permeability to oil and the relative permeability to water whenboth oil and water are present in the pore spaces seldom equals thepermeability of the formation with only one fluid present. In almost allcases the sum will be less.

These flow rates are rates after the preceding fluid had ceased to flowfor practical purposes. This does not mean that the other fluid iscompletely washed out by the flow. On the contrary, an equilibrium isreached whereby there is an irreducible saturation established. Thenon-flowing fluid is present even if it is no longer mobile. The wettingfluid usually clings to the capillary walls while the non-wetting fluidis usually present as globules trapped in pore enlargements.

Examples 49 through 51 not only show that the generally undesirable oilwetting by the organic polycationic polymers is not likely but that theycan improve the ratio of water to oil produced from the formation. Thisis a distinct advantage.

Table 8A, Examples 52A-52C, are examples of polymers containing esterand ether linkages. These condensates contain tall oil or tall oilcondensates. They gave good protection to the clays and displayed goodresistance to being washed off with acid.

There was concern about the long carbon chains of tall oil causing oilwetting. However, Examples 52A and 52B indicate water wetness and 52Bshows a "neutral" wetness.

Table 9, Examples 53-61, illustrates clay stabilization tests made onBerea cores.

The Berea formation is found in the state of Ohio and vicinity. It isoften used in the petroleum industry as a standard for scientific and/orengineering testing. Natural formations often vary from one cubic footto another. Differences are noticeable in the same block 6"×8"×6" offormation. Some Berea sections do not contain sufficient clay to bewater sensitive. The sections selected for testing were tested prior touse to be reasonably certain that they were sensitive to plugging withfresh water.

Example 53 establishes that the cores from this block of Berea sandstoneare sensitive to fresh water flow. Example 54 is also a control test. InExample 54 acid is used after calibration. Although there was only about2.8% acid solubility, it must be in a strategic location in thecapillaries because the flow rate doubled after acid. As can be seen inFootnote a, brine was used to ascertain the results of acidizing. Thefollowing fresh water flow phase indicates that although the acid openedthe core considerably, the clays are still in condition to doconsiderable damage to the permeability.

Examples 55 through 58 indicate that the carbonate content of the coreinterferes with injection of the inorganic polycationic polymer unlessacid is used as the solvent. If the carbonate content were higher than2.8%, say 10%, the acid solvent would not be sufficient.

Example 59 shows that hydroxy aluminum can treat these particular cores.The acid solubility of 2.8% is well within the expected tolerance of 5%for hydroxy aluminum. The use of an acid carrying fluid would alter thehydroxy aluminum prior to injection into the core.

Examples 60 and 61 show that pH is not a factor in the treatment ofclays with an organic polycationic polymer. Good initial fresh waterflow rates result without resorting to acid carrying fluids.

Table 10, Examples 62-68, illustrates the remedial treatments to correctprevious damage to permeability of Berea cores.

It is believed that prevention of permeability loss caused by swellingand/or migrating clays and other fines is the best method of insuringcontinued production of a well. However, often it is necessary to treatpreviously damaged formation.

Examples 62, 63 and 64 are controls that indicate that the cores can bedamaged by fresh water, that treatment with brine is not effective, and,finally, that HCl is of considerable aid in opening the core again butthe core permeability is not permanently protected.

Comparing Examples 63, 65 and 66, the organic polycationic polymerappears to have provided good remedy to the damage. Then comparingExamples 64, 67 and 68, acid alone provides good initial opening of thecore but the organic polycationic polymer seems to give better long termresults.

Table 11, Examples 71-74, illustrates the use of alcohol or organicpolar solvents other than water such as normally liquid substitutedhydrocarbons.

In formations that produce no sand as long as only hydrocarbons areproduced but disintegrate from their own formation water when the watertable rises and water production begins, aqueous preparations of organicpolycationic polymers can prevent the disintegration without the aqueouspreparation itself causing disintegration. However, some well operatorsare fearful about introducing any aqueous fluid at all, even thosedesigned to prevent disintegration of the formation by water wetness. Inaddition, it is possible that extremely water sensitive formations couldexist. Therefore, to allay fear and avoid even the possibility ofdeconsolidating extremely water sensitive formations, an organicpolycationic polymer can be dissolved in alcohol, ketone, monoethers ofglycol, or other non-aqueous solvents that provide sufficient solubilityfor the polymers and the resulting essentially non-aqueous solution ofpolymers used to treat the formation.

We claim:
 1. A method of treating a clay-containing earth formation forthe purpose of preventing or at least reducing the swelling, migrationand/or dispersion of said clay to thereby stabilize said formation, saidmethod being comprised of contacting said clay in said formation with aneffective amount of an organic polycationic polymer dispersed ordissolved in a carrier fluid, said contacting being for a timesufficient for said organic polycationic polymer to replace clay cationsto thereby transform said clay to a more stable form wherein saidorganic polycationic polymer contains repeating monomer units selectedfrom the group consisting of: ##STR23## wherein: X is an anion selectedfrom halides, nitrate, sulfate, methosulfate, bisulfate, and carbonate;nis an integer equal to the number of monomer units in said polymerrequired to produce a molecular weight in the range of from about 800 to3,000,000; and m is an integer equal to the number of said anionsrequired to maintain electronic neutralityand further wherein the ratioof the total number of nitrogen atoms in said polymer to the totalnumber of carbon atoms in said polymer is in the range of from about 1to 2 to about 1 to
 36. 2. The method of claim 1 wherein said carrierfluid is aqueous and the concentration of said polymer in said carrierfluid is in the range of from about 0.01 to about 25% polymer by volumeof said carrier fluid.
 3. The method of claim 2 wherein said aqueouscarrier fluid is a saline solution containing up to about 40% salt byweight wherein said salt is selected from alkali metal, alkaline earthmetal and ammonium halides, sulfates, carbonates and mixtures thereof.4. The method of claim 2 wherein said aqueous carrier fluid is an acidsolution selected from the group consisting of of acetic, formic,hydrofluoric, hydrochloric, nitric, phosphoric, sulfuric and mixturesthereof.
 5. The method of claim 2 wherein said aqueous carrier fluid hasa pH in the range of from about 5 to about 9.